Question

In an interference experiment third bright is obtained on screen with light of 5000 Å. What should be the wavelength in order to obtain 4^th bright at same point –

• A. 6500Å
• B. 3750 Å
• C. 5000 Å
• D. None of these

Answer 1

Answer: (B)

3750 Å

Answer 2

$\frac{\mathbf{3D \times 5000Å}}{\mathbf{d}}$ = $\frac{4D\lambda}{d}$

̃ l = 3750 Å